It got cold in the winter. Cold enough to freeze a nearby lake. Local villagers had discovered a convenient way to keep warm in the winter by mining locally available “magic” rocks. The magic rocks seemed to enhance the warmth of the local fire-pit.
For generations the village folks had mined weird glowing green rocks, an amalgam containing uranium and other minerals. They would take the rocks and dump them in the middle of the village where there was a large campfire eternally aflame. The molten rocks from the campfire would seep into the ground piling up in an underground chamber directly below the centre of the village.
One day, after a number of generations had used the fire pit, there was a massive explosion underground. The uranium seeping into the ground from the molten rocks ignited in an atomic explosion. The shape of the underground chamber focused most of the explosive force downwards. The explosion lifted the entire village into the air where it was eventually propelled almost into orbit by the burning uranium. As the uranium powered “rocket” burned itself out, the village came back down and landed in a different part of the continent.
Tribal elders were astounded and excited by the event. They realized they may have a way of reaching the stars in the night sky.